Outdoor swimming pools and other outdoor structures located in geographic regions having a winter season are typically protected from the elements or "winterized" to prevent them from being damaged and, particularly with respect to pools, to reduce the amount of clean-up operations necessary to place them in condition for the warm summer season. For example, in the case of completely or partially uncovered swimming pools, not only rain or snow but also debris in the form of fallen leaves, dirt, or other particles carried by wind and rain, tend to collect therein and make the clean-up job upon re-opening the pool much more complicated and time-consuming. Thus, it is extremely advantageous to provide a cover or other protection to limit the amount of debris which may be collected in the pool to the smallest practical extent. Pool covers are also an important safety feature to prevent accidental drownings when the pool is not in use. If the pool cover is properly held down around its perimeter, it will support the weight of a person or animal that may accidentally fall in the pool. Therefore, it is extremely important to provide a reliable securing method throughout the period when the pool is not in use and the cover is in place.
Covers or tarpaulins are also used to cover items that are stored out of doors; such items as lawn furniture, motor vehicles, recreational vehicles, woodpiles and other articles too numerous to specify more particularly herein. However, the heavy winds of winter and uneven collection or pooling of water may also lead to the covers or tarpaulins being partially or completely removed front the items which they are supposed to protect from the elements.
Techniques for protecting swimming pools in geographic areas where such pools are not used year-round fall into three general categories. The first technique comprises the use of a mesh cover which allows precipitation, such as rain, to pass therethrough and collect in the pool, the mesh cover being held in place by resilient tie members, such as springs or bungee cord attached to the perimeter of the cover and held taut by hooking the springs or bungee cords to anchoring members, such as pop-up pins set at spaced intervals in a deck surrounding the pool, or other suitable anchoring means provided either in the deck or driven into the ground surrounding the deck, the cover being of a size sufficient to cover the pool and a marginal portion thereof surrounding the pool. Although this technique prevents large sized debris from collecting in the pool, dirt and small particulate and airborne algae spores are nevertheless able to pass through the mesh cover and collect in the pool, thereby significantly increasing the required clean-up efforts at pool-opening time.
A second protective technique utilizes a mechanized, automatically opened cover, usually formed of rigid vinyl, which is held in place by means of rollers arranged within a guide track that is secured to the deck surrounding the pool or the walls of the pool. Covers of this nature are significantly more expensive than flexible plastic covers.
The third and, by far, the most popular technique employs a flexible plastic cover which rests upon the surface of the water in the pool and which typically extends approximately two feet beyond the perimeter of the pool and onto a deck or other surface surrounding the perimeter. The cover is held in place typically by means of a plurality of elongated water-filled flexible tubes or balloons which are available in various lengths and are most often made of vinyl sheeting with heat-welded seams. The tubes are most often between three and four feet in length and require a valve or closure which prevents the escape of water. The vinyl sheeting from which the tubes are typically formed has a specific gravity greater than one and a properly filled tube is negatively buoyant in water, i.e., will sink in water. A plurality of tubes, often more than one hundred linear feel (100 ft.) worth or approximately twenty five (25) water-tubes, having the afore-described structure are deployed by filling them with water, closing the valves and placing on the outside perimeter of the cover, i.e., that portion of the cover which overlies the pool deck or surface surrounding the perimeter of the pool.
Since water-filled tubes have a tendency to roll under the influence of wind and/or the pitch of the deck, they quite frequently will fall into the pool or roll off the cover's perimeter onto the ground surrounding the pool deck. If the tubes roll onto the ground from the cover, then the cover is easily pushed around by the winter winds and more often than not ends up on the bottom of the pool. If the water-tubes roll into the pool, they sink to the bottom of the pool due to their negative buoyancy, usually taking the cover and all the debris accumulated thereon to the bottom with them and making it extremely difficult to remove the cover from the pool or the water from within the tubes. It thus becomes virtually impossible to lift the tubes out of the water since it is not practical to drain the water from within the tubes when they are beneath the surface of the water. In apparent recognition of the problem of rolling water-tubes, a technique was developed as disclosed in U.S. Pat. No. 3,711,873 to Katzman, issued Jan. 23, 1973 for providing holding means referred to as "cover loops" which are secured at spaced intervals along the perimeter of the cover. Many pool cover manufacturers have integrated loops into the edges and around the perimeters of their covers. In theory, the loops are used by stringing each of the water-tubes through at least one of the loops, either prior to or after filling the water-tube with. The cover loops are intended to help keep the water-tubes from rolling off of the cover and onto the ground surrounding the deck of the pool. Even if the water-tubes do roll off the cover onto the ground, the cover is theoretically still held in place by the loops around the water-tubes. However, in practice, it has been found that the loops may contribute to loss of water from the water-tubes by increasing the strain placed on the tubes' valves. Additionally, the loops cannot prevent the water-tubes from rolling into the pool itself, and they usually compound the problems referred to hereinabove by almost ensuring that the pool cover will be dragged into the pool by the water-tubes due to its attachment via the cover loops.
Another technique utilized to overcome the disadvantage of a tube which tends to roll, comprises a pair of tubes joined to one another along a longitudinal seam. This technique suffers from the disadvantage that it tends to weaken both tubes along the seam. Still another technique is to weld the tube to the cover. However, this adds considerably to the cost of manufacturing the cover and it does overcome many of the disadvantages of the water-tubes which include the fact that the flexible vinyl utilized to form the tubes is highly susceptible to abrasion, seam-splitting and leaking around the valve. Any openings in the tube due to a poor or damaged seam or a leak in the valve allows the water to leak from the tube, rendering the tube useless as a means of anchoring the cover. Another problem common to all of the water-tubes is leaking around the valve dine to poor welding or due to damage to the valve. The most common valve utilized is referred to as a Roberts valve.
Flexible plastic mesh covers can also be used in the same manner as solid vinyl pool covers, i.e. held in place by water-tubes, but these too require significant anchoring to prevent them from being displaced by heavy winds and to prevent debris thereon from being swept into the pool.
As mentioned briefly hereinabove, another problem encountered when using water-filled tubes is leaking from faulty seams which defect typically does not become evident until after installation, and most often doesn't manifest itself until during the cold winter months. Additional disadvantages to using soft-walled water-tubes include their susceptibility to abrasion damage from contact with rough surfaces, such as a concrete walk. This kind of abrasion typically occurs during installation or removal of the water-tubes. The water-tubes are also susceptible to damage from birds, rodents, raccoons, dogs, and other animals, as well as insects, such as termites and ants. The water-filled tubes are also susceptible to splitting along their seams due to the expansion of freezing water. Leakage from the plastic tubes is typically slow and it is often a practical impossibility to locate small holes and it is extremely difficult to properly patch holes in the walls of the water-tubes or leaking seams.
In the event that one or more, or, in fact, all of the water-filled plastic tubes are accidentally drained of water, the cover may be damaged by being blown off the pool or sliding into the pool due, for example, to the weight of snow, rain, water or other debris collecting on the cover. In those cases where water-filled tubes fall into the pool, the tubes sink to the bottom of the pool and, when secured to the cover by cover loops or weldments, drag the cover to the bottom of the pool.
Under the best of circumstances it is an extremely tedious job to remove water-filled plastic tubes and the cover from the pool. It is much more so when the water-tubes and the cover have become partially or completely submerged in the pool to be opened or recovered. In addition, the water in the pool is most likely contaminated with debris, leaves, and dirty water which was previously collected upon the top surface of the cover, further contributing to the laborious job of cleaning the pool. More importantly, the pool itself may be damaged by the debris or subsequent exposure, necessitating potentially extremely expensive repairs.
Even assuming that damaged plastic tubes are replaced with new tubes before the cover has blown off the pool or into the pool, it is still an extremely tedious job to replace water-tubes during the fall, winter or spring seasons. The highly probable need to do so when utilizing water-tubes as pool cover or ground cover anchors significantly reduces their desirability as anchoring means.
Emptying those water-tubes that haven't emptied themselves by late spring-time is accomplished by opening the Roberts valve, a sometimes difficult task. Once the valve is open, the end of the water-tube farthest from the Roberts valve is lifted and is held a significant spaced distance above the ground until the water runs out of the valve opening which is typically a small opening. Since a water-tube having a length of four feet may easily weigh between 40 and 80 pounds, and since an average in-ground pool may require twenty to thirty such bags, the energy required for tile task can be quite tiring. The water remaining in the tube, after the tube is drained, is removed by pressing the tube flat. The tube must then be cleaned and scrubbed, set out to dry and then folded or rolled up for storage during which time it is susceptible to damage from rodents, insects and the like and may be further subjected to staining due to fungus growth along the interior surface of the tube caused by incomplete water drainage. The fungus grows through the plastic to the outer surface yielding an unsightly stained appearance.
It is thus advantageous to provide a water-filled enclosure capable of maintaining a pool cover or ground cover in place, is inexpensive to rpoduce and ship and yet overcomes all of the disadvantages of the water-tubes presently known.